1. Field of the Invention
The present invention relates to an information storage medium such as an optical disk of a high recording density type, which is capable of recording information such as video information, audio information and the like at a high density, and which is represented by a DVD (Digital Video or Versatile Disk). The present invention also relates to a recording apparatus for recording the information onto the information storage medium, and a reproduction apparatus for reproducing the information from the information storage medium.
2. Description of the Related Art
Conventionally, a so-called LD (Laser Disk) and a so-called CD (Compact Disk) are generalized as optical disks, on which information such as video information, audio information and the like is recorded.
On the LD or the like, the video information and the audio information are recorded together with time information indicating a time at which each information is to be reproduced with respect to a reproduction start position of each LD or the like, serving as a standard position. Thus, in case of the CD for example, other than a normal reproduction to reproduce the recorded information in the order of recording, various special reproductions are possible, such as a reproduction to extract and listen to only desirable music pieces out of a plurality of recorded music pieces, a reproduction to listen to the recorded music pieces in a random order and so on.
However, there is a problem that, according to the above mentioned LD or the like, a so-called interactive and variegated reproduction is not possible in which the audience can have a plurality of selection branches as for the video or audio information to be displayed or sound-outputted and in which the audience can select them to watch or listen to it.
Namely, it is impossible for a user to choose the language used in the subtitle on the screen (e.g., from subtitle of Japanese and the original language) in the case of watching a foreign movie recorded on a LD or to choose the voices of a song (e.g., from English voices or Japanese voices) in the case of listening to the music recorded on a CD.
Nowadays, apart from the above-mentioned conventional CD, it is proposed and developed a DVD which is an optical disc which disc size is identical to CD and which recording capacity is enhanced to be approximately ten times larger than that of CD. By recording the subtitles and/or voices of plural languages on the DVD, the user can select one of those plural languages to enjoy the interactive and variegated playback.
In the DVD, plural audio information of various attributes such as the coding mode, the sampling frequency, the quantization bit number, the number of channels, the emphasis added or not added and the like (hereinafter referred to as “audio attribute”) may be recorded in a mixed manner on a single DVD.
However, when reproducing audio information of different audio attributes, the reproduction apparatus should perform appropriate reproduction in conformity with those different audio attributes. For example, when reproducing and outputting audio information from the speaker, it is required to convert digital audio information recorded on the DVD into analog audio information and then supply it to the amplifier and the speaker. In such a case, if two songs to be successively reproduced have different sampling frequencies (e.g., the first song has the sampling frequency of 48 kHz and the second song has the sampling frequency of 96 kHz), the reproduction apparatus recognizes the different sampling frequencies for the first time when it reads audio data of the second song, after the playback of the first song, and then starts the processing to change the clock frequency of the D/A converter from 48 kHz to 96 kHz. However, it takes some time for the PLL (Phase Locked Loop) circuit to lock-in the changed frequency, and hence the frequency change may not be completed before starting the playback of the second song, thereby resulting in an incorrect playback of the initial portion of the second song. Such a problem may take place not only for the sampling frequency but for the difference of other audio attributes such as the quantization bit number, the emphasis added or not added, and the like.